A Real-Time Fallout Monitor for 5–250 Micrometer Particles

Abstract

In many assembly and clean room applications it is desirable to continuously monitor fallout or sedimentation of large particles, typically greater than 5 microns in diameter. The accepted technique for monitoring sedimentation today is to collect particles on a witness plate and count them at periodic intervals. In many cases, however, it is important to observe sedimentation in real-time. For example, in a location where machinery operates, real-time monitoring can provide immediate warning of a problem.